• NOTCH3 (Neurogenic locus notch homolog protein 3) is one of four mammalian Notch proteins, which acts as signaling receptors to control cell fate in many developmental and adult tissue contexts. Notch is a transmembrane, developmental signaling receptor, which plays many crucial roles in developmental patterning, cell fate decisions and regulation of cell survival and proliferation.
• Genetic studies have shown that Notch3 gene knockouts are viable and have limited developmental defects, focused mostly on defects in the arterial smooth muscle cell lineage. Notch3, in collaboration with other Notch proteins, is involved in stem cell regulation in different tissues in stem cell regulation in different tissues, and it also controls the plasticity of the vascular smooth muscle phenotype involved in arterial vessel remodeling. 
• The exons 1-27 of mouse Notch3 gene that encode signal peptide and extracellular domain were replaced by human counterparts in B-hNOTCH3 mice.
• Mouse Notch3 mRNA were detectable only in wild-type mice. Human NOTCH3 mRNA were detectable only in B-hNOTCH3 mice but not in wild-type mice.

Gene targeting strategy for B-hNOTCH3 mice. The exons 1-27 of mouse Notch3 gene that encode signal peptide, extracellular domain were replaced by human counterparts in B-hNOTCH3 mice. The genomic region of mouse Notch3 gene that encodes transmembrane domain and cytoplasmic portion were retained. The promoter, 5’UTR and 3’UTR region of the mouse gene were also retained. The chimeric NOTCH3 expression was driven by endogenous mouse Notch3 promoter, while mouse Notch3 gene transcription and translation will be disrupted. 

Strain specific analysis of NOTCH3 mRNA expression in wild-type C57BL/6JNifdc mice and homozygous B-hNOTCH3 mice by RT-PCR. Brain RNA were isolated from wild-type C57BL/6JNifdc mice (+/+) and homozygous B-hNOTCH3 mice (H/H). Mouse Notch3 mRNA were detectable only in wild-type mice. Human NOTCH3 mRNA were detectable only in B-hNOTCH3 mice but not in wild-type mice.